Welcome to the world of Fisher.
Tons of info around here, just search in the Fisher forum using the words F75, F70, settings, iron, trash and the like.
The F75 and F70 are similar so lots of stuff about settings is shared but there are some differences.
The DST makes them really quiet, a bunch of old owners got back into them after selling off their older more chatty units long ago and seem pretty happy with the upgrade.
I run with an F70 so I don't have DST but no matter, it still has conquered every difficult site, condition or soil type I have brought it to so far.
The factory settings are great, they set them up this way for a reason and they should find most everything we are likely to go after so get used to using it that way at first...plenty of time to tweak them as you get comfortable.
The different tone choices are something you might want to play around with and see if you like one more over another.
I use 3H and 4H when sweeping parks for clad, older coins and jewelry.
Love the tones, I am able to watch the coil and just listen to the tones and then check out the screen if I hear a good one so a pretty fast and efficient way to hunt.
If you ever had problems finding nickels in the past you won't with these two settings because nickel area targets are changed to high tones using them.
Not only has that high tone alerted me to more nickels but a few extra gold pieces too.
Thinking about it that 4H tone found a couple of nickel area gold targets that I might have noticed using something else but definitely noticed when they came in as that high tone.
Just about enough gold to pay for my rig, actually.
DP is a totally cool way to hunt, a different tone depending on the conductivity reading from low to high and many use only this but I have not gotten the hang of it just yet although I don't use it all the time.
DP is actually the only tone setting directly tied into the screen so I guess one of the fastest but all the tone choices are blazing fast on this machine.
The new FA process is supposed to be super fast but not the deepest choice.
I have used them all but I have 2 favorite settings I use most of the time...all metal with most everything else turned up to max and 1 tone...monotone when using disc and hunting in trash or iron heavy sites.
Both responsive and fast but all metal takes some getting used to because of how this thing will pick up the huge volume of metal from tiny to large and shallow to deep in the soil.
They will come fast and furious but practice and it gets easy to notice the good stuff.
On monotone I generally don't go much higher than 1 on the disc, experimenting with 0 disc but more chatter with that, but I like it because is close to what happens in all metal, I don't miss much and a little quieter than using all metal and less fatiguing to listen to for long periods for me.
I hunt in very difficult mineralized soil filled with extra iron so to me these settings seem to work well with extra piercing and ID ability...In much better mild Midwest soil all settings worked great and got deep.
1F and 2F have their advantages, when hunting in the woods I like to use one if them from time to time.
As always try out a few for yourself, eventually you will find what you like the most and there really doesn't seem to be any really wrong settings...everything seems to work well.
If you come across some really difficult and challenging sites that is when having experience tweaking this thing will have an advantage, for general hunting most everything and any way you set it seems to do the job.
Have fun, experience, learn, ask questions.